EnsureDataBound.cs

    public class EnsureDataBound : Control
    {
        private int _count;

        public bool AllowMultiple { get; set; }
        public bool EveryPostBack { get; set; }
        public When When { get; set; }

        public override void DataBind()
        {
            if (!AllowMultiple && _count > 0) return;
            _count++;
            base.DataBind();
        }

        public void ReDataBind()
        {
            _count++;
            base.DataBind();
        }

        protected override void OnInit(EventArgs e)
        {
            if (When == When.Init && (EveryPostBack || !Page.IsPostBack)) DataBind();
            base.OnInit(e);
        }

        protected override void OnLoad(EventArgs e)
        {
            if (When == When.Load && (EveryPostBack || !Page.IsPostBack)) DataBind();
            base.OnLoad(e);
        }

        protected override void OnPreRender(EventArgs e)
        {
            if (When == When.PreRender && (EveryPostBack || !Page.IsPostBack)) DataBind();
            base.OnPreRender(e);
        }
    }

    public enum When
    {
        Load,
        Init,
        PreRender
    }